How to merge 2 videos for one screen? - swift

Question

I am making a karaoke app. I want to merge users videos like karaoke videos. Left side of screen one user and right side of screen other user. I can merge videos and audios but i did not understand how can i merge videos. Many of examples show that merge videos sequently.
func mergeMutableVideoWithAudio(videoUrl:URL, audioUrl:URL){
let mixComposition : AVMutableComposition = AVMutableComposition()
var mutableCompositionVideoTrack : [AVMutableCompositionTrack] = []
var mutableCompositionAudioTrack : [AVMutableCompositionTrack] = []
let totalVideoCompositionInstruction : AVMutableVideoCompositionInstruction = AVMutableVideoCompositionInstruction()
//start merge
let aVideoAsset : AVAsset = AVAsset(url: videoUrl as URL)
let aAudioAsset : AVAsset = AVAsset(url: audioUrl as URL)
mutableCompositionVideoTrack.append(mixComposition.addMutableTrack(withMediaType: AVMediaTypeVideo, preferredTrackID: kCMPersistentTrackID_Invalid))
mutableCompositionAudioTrack.append( mixComposition.addMutableTrack(withMediaType: AVMediaTypeAudio, preferredTrackID: kCMPersistentTrackID_Invalid))
let aVideoAssetTrack : AVAssetTrack = aVideoAsset.tracks(withMediaType: AVMediaTypeVideo)[0]
let aAudioAssetTrack : AVAssetTrack = aAudioAsset.tracks(withMediaType: AVMediaTypeAudio)[0]
do{
try mutableCompositionVideoTrack[0].insertTimeRange(CMTimeRangeMake(kCMTimeZero, aVideoAssetTrack.timeRange.duration), of: aVideoAssetTrack, at: kCMTimeZero)
try mutableCompositionAudioTrack[0].insertTimeRange(CMTimeRangeMake(kCMTimeZero, aVideoAssetTrack.timeRange.duration), of: aAudioAssetTrack, at: kCMTimeZero)
}catch{
}
mutableCompositionVideoTrack[0].preferredTransform = aVideoAssetTrack.preferredTransform
totalVideoCompositionInstruction.timeRange = CMTimeRangeMake(kCMTimeZero,aVideoAssetTrack.timeRange.duration )
let mutableVideoComposition : AVMutableVideoComposition = AVMutableVideoComposition()
mutableVideoComposition.frameDuration = CMTimeMake(1, 30)
mutableVideoComposition.renderSize = CGSize(width: 480, height: 480)
mergedAudioVideoURl = NSURL(fileURLWithPath: NSHomeDirectory() + "/Documents/FinalVideo.mp4")
let assetExport: AVAssetExportSession = AVAssetExportSession(asset: mixComposition, presetName: AVAssetExportPresetHighestQuality)!
assetExport.outputFileType = AVFileTypeQuickTimeMovie
assetExport.outputURL = mergedAudioVideoURl as URL
removeFileAtURLIfExists(url: mergedAudioVideoURl)
assetExport.shouldOptimizeForNetworkUse = false
assetExport.exportAsynchronously { () -> Void in
switch assetExport.status {
case AVAssetExportSessionStatus.completed:
let library = ALAssetsLibrary()
library.writeVideoAtPath(toSavedPhotosAlbum: self.mergedAudioVideoURl as URL!, completionBlock: { (bool) in
DispatchQueue.main.async {
UserModel.sharedInstance.isVideoMerged = true
let effect = self.view.subviews.last
effect?.removeFromSuperview()
self.popupViewController.dismiss(animated: true, completion: nil)
}
})
print("-----Merge mutable video with trimmed audio exportation complete.\(self.mergedAudioVideoURl)")
case AVAssetExportSessionStatus.failed:
print("failed \(String(describing: assetExport.error))")
case AVAssetExportSessionStatus.cancelled:
print("cancelled \(String(describing: assetExport.error))")
default:
print("complete")
}
}
}